title: Dual effect of lobeline on α4β2 rat neuronal nicotinic receptors.
abstract: The effect of lobeline on rat α4β2 nicotinic receptors expressed in COS cells was studied using the patch-clamp technique. Currents were recorded in whole-cell mode 2-4 days after cell transfection by plasmids coding the α4β2 combination of receptor subunits. In cells sensitive to acetylcholine, the application of lobeline evoked minor responses (up to 2% of maximal acetylcholine response). When acetylcholine was applied to the background of an already running application of lobeline, acetylcholine responses were inhibited in a concentration- and time dependent manner. However, when lobeline was applied simultaneously with acetylcholine without any prepulse or during an already running application of acetylcholine, the acetylcholine responses were potentiated up to 300-600% of that of the control. The site of lobeline action overlaps with the cholinergic site, as was proven by the partially protective effect of (+)-tubocurarine. Thus, lobeline can apparently desensitize receptors when applied alone (inhibition) whereas its binding to a second agonist site with the first one already occupied by acetylcholine leads to channel opening (potentiation).
authors.affiliation: Institute of Physiology Academy of Sciences of the Czech Republic v.v.i., Vídeňská 1083, 14220 Prague, Czech Republic.
authors.forename: Martina
authors.initials: M
authors.lastname: Kaniaková
authors.forename: Jiří
authors.initials: J
authors.lastname: Lindovský
authors.forename: Jan
authors.initials: J
authors.lastname: Krůšek
authors.forename: Svatopluk
authors.initials: S
authors.lastname: Adámek
authors.forename: František
authors.initials: F
authors.lastname: Vyskočil
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D004357:Drug Synergism; D008120:Lobeline / Q000494:pharmacology*; D009474:Neurons / Q000378:metabolism*; D018722:Nicotinic Agonists / Q000494:pharmacology*; D018733:Nicotinic Antagonists / Q000494:pharmacology*; D051381:Rats; D011978:Receptors, Nicotinic / Q000378:metabolism*
chemical_list: D018722:Nicotinic Agonists; D018733:Nicotinic Antagonists; D011978:Receptors, Nicotinic; C403531:nicotinic receptor alpha4beta2; D008120:Lobeline; D000109:Acetylcholine